Unbalance sensing arrangement for use in laundry machines



P 1959 J. BOCHAN 2,905,324

UNBALANCE SENSING ARRANGEMENT FOR USE IN LAUNDRY MACHINES Filed April 14, 1958 2 Sheets-Sheet 2 6 Fl 6. Z.

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INVENTOR.

J'OHN BOCHAN H l 25 ATTORNEY United States UNBALANCE SENSING ARRANGEMENT FOR use IN LAUNDRY MAcnmrs John Bochan, Louisville, Ky., nsslgnor to General Electrlc Company, a corporation of New York Application April 14, 1958, Serial No. 728,301

6 Claims. (Cl. 210-149) This invention relates to automatic laundry machines of the type having a rotatable clothes basket WhlCll is rotated at a relatively low speed to tumble the clothes in order to wash them and at a higher speed for centrifugal extraction of liquid from the clothes; more particularly, it relates to provision in such machines of improved means, sensitive to excessive unbalance VlblailOllS resulting from unbalanced clothes loads during the centrifugalextraction, for causing said vibrations to effect actuation of a switch to remedy the situation.

Many domestic washing machines provide a centrifugal extraction of liquid from wet clothes by means of a high speed rotation. Most of these machines, in turn, provide some type of safety device for correcting the situation when the clothes are so distributed in the clothes receptacle during high speed rotation that excessive unbalance is present and vibrations harmful to the machine could result therefrom. A frequently used arrangement is to provide a member positioned to be sensitive to the vibrations so that it moves substantially in proportion thereto. When the vibrations attain a certain limit the movement of the sensing member is transmitted by a suitable device to actuate a switch. This in turn provides some suitable corrective action. For

instance, the machine may shut oif without further op-.

eration until it is started again by an operator; or it may return to a low speed for redistribution of the clothes and then again attempt a high speed operation; or it may stop any further acceleration of the clothes receptacle, so that the centrifugal extraction is carried out at the maximum speed allowable in view of the unbalance present. Whatever the remedy, it is normally provided by the actuation of theswitch in response to the movement of the vibration sensing member as transmitted through the intermediate device. Since the amount of free space that the sensing member can be moved before switch actuation is the vital element in determining the maxi mum vibration permitted, it will be seen that setting of the intermediate device so that it is movable only a predetermined amount before switch actuation is of prime importance. However, laundry machines have many moving parts, several of which move at relatively high speed and are quite heavy; as a result, the various parts tend to adjust relative to each other during the life of the machine. Such adjustments can, of course, change to a substantial extent the size of the vibrations which will cause actuation of the switch. In the past, this problem has been met by providing a manual adjusting mechanism and thereby correcting the setting of the device whenever necessary. This manual adjustment is, however, quite time consuming, especially if needed at all frequently. In addition, by the time the manual adjustment is made, the size of the maximum vibrations has changed to a noticeable extent, thus causing a departure from optimum operation of the machine until the adjustment is made.

It is therefore an' object of this invention to provide a hit construction whereby the device which its the motion from the vibration sensing means to actuate the switch is easily and automatically adjusted once it has been set a first time.

A further object of the invention is to provide a construction wherein the adjustment of the motion transmitting device is effected automatically as an integral part of the operating cycle of the machine.

In accordance with the invention, I provide a laundry machine having an article receptacle with means for rotating the receptacle at high speed in order to extract liquid from the clothes. To protect the machine against harmful vibrations as a result of unbalanced leads, I provide means which are movable in response to vibrations of the receptacle, an unbalance switch which operates to protect the machine, as discussed above, and a suitable arrangement to transmit the movement from the movable means to the unbalance switch. This arrangement includes a first member intermediate the movable means and the unbalance switch, positioned to be engaged by the movable means; a second intermediate member positioned to operate the switch upon being moved a predetermined amount; and biasing means for biasing the members apart, the first member toward the movable means and the second member toward the switch. I also provide limiting means secured to one of the members and engaging the other member so as to limit the distance the members are biased apart. The first member is secured to the limiting means by an arrangement which includes a first part secured to the first member, a second part secured to the limiting means, and a quantity of solder securing adjacent surfaces of the two partstogether. Under normal circumstances, this provides a substantially rigid connection to provide the necessary predetermined relationship between the first and second members. In addition, I provide heating means adjacent the two soldered parts which is effective when operated to melt the solder. When this occurs, the biasing means is free to move the members apart relative to each other so as to take up any play which may occur as a result of wear of the machine.

in the preferred embodiment of the invention, second biasing means stronger than the first biasing means, are provided to bias the second member away from the switch. With this provision, when the solder is melted the first biasing means move the first member against the movable means-if it is not already there-without having any effect on the relationship of the second member and the switch. In this manner, the device for transmitting motion from the vibration sensing means to the switch is always self-adjusting so that the switch is tripped at substantially the same limit of vibration throughout the life of the machine.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My'invention itself, however, may best be understood by reference to the following description taken in conjunction with the accompanying drawings.

In the drawings, Fig. l is a front elevational view of a' domestic laundry machine showing vibration sensing means for transmitting movement therefrom to a switch in accordance with this invention, certain surfaces of the view being broken away in order better to illustrate certain details;

Fig. 2 is an enlarged side elevational view of the machine of Fig. l with the side panel removed, the View being partly in section and having certain surfaces broken away to illustrate certain details;

Fig. 3 is a fragmentary plan view of drive means which may be included in the machine;

Fig. 4 is a front elevational view of a preferred embodiment of my improved unbalance device, the view s,soo,sss

3 also showing schematically a control circuit suitable for use in a machine embodying my device; and

Fig. is a view of a portion of the improved unbalance device along line 5-5 in Fig. 6.

Referring now to Figs. 1 and 2, I have shown my invention in one form as applied to a domestic laundry machine 1 comprising a combination washer and dryer. The machine 1 includes an outer cabinet 2 which is mounted on a supporting base structure 3. Access to the machine for loading and unloading of clothes is provided by a hinged door 4 disposed in the front wall of the cabinet. A backsplasher 5, mounted at the top of the cabinet, serves as a mounting means for suitable operator controls for the machine. These controls may, for example, comprise the rotatable dials 6 and 7 and pushbuttons 8.

The machine 1 is of the type which includes a clothes basket rotatable about a non-vertical axis; specifically, referring to Fig. 2, it includes a perforated basket 9 which is d'uposed for rotation about a generally horizontal axis. The basket 9 is mounted within an imperforate tub structure 18 which encloses it on all sides. Thebasket is rotatably supported from the tub structure by a hor1- mentally extending shaft 11 which is mounted in an elongated bearing 12 hung from the rear wall 13 of the tub structure. The shaft 11, as well as supporting the basket, also serves as a means for turning it during operatin! of the machine. The tub and basket are provided, rsqaectively, with openings 14 and 15 in the front walls thereof, the openings being aligned with the door opening in the front wall of the cabinet 2 so that clothes may be placed into or removed from the basket. The door 4 seals against the gasket 16 around the tub opening 14 to close off the tub completely during operation of the machine.

'Ibb10issupportedfrombase3bymeansofa plurality of brackets or arms 17 which are mounted on upstanding plates 18 fixedly attached to the base 3. Four of these arms 17 are provided, two being secured to each side of the tub. The arms on the opposite sides ofthetubarespacedapartsothatthetubinetiect is supported near its front and near its rear on each side thereof. Although the arms 17 can be secured directly to the wall of tub 10, preferably, and as shown, the arms 17 are attached thereto by means of suitable brackets 19. With the tub supported in the manner shown, it is able to vibrate sideways in a plane parallel to the front of the machine if the basket 9 should be imbalanced during a high speed rotation thereof. The arms 17 are relatively long compared to their width, and they flex so as to allow slight sideways vibration of the tub relative to the base 3. However, the arms 17 are efiective substantially to prevent vibration of the tub both from front to rear and in the vertical direction since they are not at all flexible in these d' ections. As is more fully explained hereinafter, I provide means for sensing the amount of sideways vibration thereby to prevent that vibration from ever becoming great enough to damage the machine or to cause it to move on the floor.

During the operation of the machine basket 9 is driven from suitable means, such as an electric motor 20, through a drive which includes a transmisison assembly 21 and a pair of flexible belts 22 and 23 (Figs. 2 and 3). Belt 22 connects the output pulley 26 'of the transmission assembly to a basket drive pulley 27 mounted on shaft 11 of basket 9. The transmission assembly 21 is of the multiple speed type, that is, the gear ratio thereof can be changed so that the basket is driven at two difierent speeds for a given speed at which the pulley 25 of that assembly is being driven.

The ratio of the transmission assembly input to output speeds is changed by any suitable means, such as spring biased solenoid operated plunger 28. When the electrically operated solenoid 29 controlling the plunger is 4 de-energized, the transmission ratio is such that the basket is driven at a suitable speed for washing and tumbling clothes, for example, revolutions per minute. However, when the solenoid 29 is energized, plunger 28 changes the ratio of the transmission so that the basket is driven at a relatively high centrifugal extraction speed, for example, 250 revolutions per minute.

The complete operation of the machine normally provides a washing period, a draining of the washing liquid, and a rinse at 45 r.p.m., all of during which basket 9 rotates at a tumbling speed of approximately 45 r.p.m., a centrifugal liquid extraction at 300 r.p.m., and, if desired, a drying period at 45 r.p.m. While variations of the sequence can be provided, it will be understood that the described sequence is typical and is provided by standard control apparatus in the usual manner.

During the operation of the machine, the various electrical components thereof are under the control of a timer operated sequence control indicated schematically at 38 in Fig. 4. A suitable sequence control and a complete circuit for a washer-dryer machine are shown, for instance, in copending application S.N. 512,612, filed June 1955 by Walter B. Gray, Jr., owned by General Electric Company, assignee of the present application, and it will be understood that in addition to the elements illustrated and described herebelow as electrically controlled by sequence timer 30, the timer also controls suitable means whereby water is admitted to and discharged from the machine and suitable means for effecting heat drying of the clothes. A water inlet connection 31 and a sheathed type electric resistance heater 32 are shown in Fig. 2. Any suitable electrically actuated means, such as a drain pump (not shown), can be used to control the discharge of water from the machine.

Referring now particularly to Fig. 4, sequence control 30, motor 20, and all the other electrical components of the system illustrated in that figure are energized from a pair of supply conductors 33 and 34. The sequence control is in series with motor 20 and causes it to be energized throughout the operating cycle of machine 1. Seqence control 30 is also in series with solenoid 29;

' in addition, solenoid 29 is connected to a terminal 35 of an unbalance switch 36 which also includes terminals 37 and 38. Terminal 37 is connected to line 34 and terminal 38 is connected to line 33 through a second timer motor 39. As will be further discussed below, switch 36 is effective to connect terminal 37 either to terminal 38 or to terminal 35; thus, when sequence control 30 permits the circuit to solenoid 29 to be completed, switch 36 causes solenoid 29 and timer motor 39 to be alternatively energized.

The switch 36 is arranged so that normally terminals 35 and 37 are in engagement so that solenoid 29 is wholly under the control of sequence control 30, terminal 38 normally being disengaged. Connection of terminal 37 to terminal 38 is achieved by depression of projecting member 40 of switch 36. Once button 40 has been depressed, terminals 37 and 38 remain in engagement until a depression of button 41 returns switch 36 to its normal position. There are, of course, many mechanisms which may be provided within switch 36 to effect the desired result.

Switch 36 is mounted on a bracket 41a secured to base 3, and is actuated by suitable movable means operative in response to vibrations of basket 9. In the present case, this is provided in the form of a depending bracket 42 secured to tub 10. Between bracket 42 and switch 36 there is interposed a suitable arrangement for transmitting a predetermined amount of movement of bracket 42 into actuation of switch 36 by depression of button 40. The

motion transmitting means, generally indicated at 43, includes an adjustable scissors arrangement in which a pair of movable members 44 and 45 are formed as arms pivotally mounted on a pin 46 which, together with the aeoasaa other parts of device 43, is supported on bracket 41a. The one arm 44 of the scissors engages the bracket 42 on tub 10 so as to be moved thereby, and the other arm 45 is actuated by arm 44 so as to operate switch button 40 upon a suflicient movement of the tub. The

' motion of bracket 42 transmitted from arm 44 to arm 45 by biasing means consisting of a coil spring 4% mounted by means of bosses 49 and 56 respectively formed on the two arms and biasing them apart, arm toward bracket 42 and arm 45 toward switch button 40. Spring 48 is strong enough so that it is not ordinarily depressed by the movement of arm 44, but, rather, transmits the movement of arm 44 to arm 45 to cause arm 45 to move against the switch button 40.

In order to adjust the scissors device 43 so that switch 36 will be operated upon a predetermined vibration of tub 10,'the normal position of arm 45 with respect to button 40 is pre-set to provide a predetermined relation between them. Depending upon the permissible vibration of the tub and the distance button 40 must be pushed into the switch housing before operating the switch, arm 45 may be preset with a predetermined gap between it and the switch button 40, or it may be set so that it directly engages the switch button.

In order to pre-set the position of arm 45 there is provided a third pivoted member 51 which is also mounted on pin 46. Member 51 has a tab 52 which extends into a curved slot 53 in arm 45. Spring 48 biased arm 45 to the right as viewed in Fig. 4, so that normally tab 69 is engaged with the extreme left hand end of the slot. With this relationship between arm 45 and member 51, it will be seen that by adjusting the position of the member 51, the normal position of arm 45 may be changed. To determine the position of member 51, adjusting means are provided including a spring 54 and an adjustable stop 55. Spring 54 is disposed between the hook So on member 51 and a projection 57 on support member 4hr, and it pulls member 51 into contact with stop 55.

In the embodiment illustrated, stop 55 comprises a movable slide which may be adjusted by means of a screw 58. Screw 58 has an eccentric shoulder (not shown) which engages the slide so that, as the screw is turned,

the slide is moved to the right or left as viewed in Fig. 4.

A tightening screw 59 is provided for bolting the slide in its final position of adjustment. Since spring 54 biases the pivoted member 51 against the slide 55, adjusting the position of the slide also adjusts the norma position of the pivoted member 51. Due to the engaging means 52 and 53 between member 51 and arm 45, this also results in an adjustment of the normal position of arm 45 relative to button 40 of unbalance switch 36.

By means of the arrangement now to be described (with reference to Figs. 4 and the final setting of arm 44 against bracket 42 may be readily accomplished at the site of installation of the machine and will be retained, together with the setting of s'irm 45 relative to switch 36, throughout the life of machine 1. Pivotably secured to arm 44 by a pin 6th is a tubular part 61 which is open at its other end 62. Part s1 is in loosely telescoping relationship with a similar part as which is pivotably secured to member 51 by a pin 64. Preferably, part 61 is provided with an opening 66 so that parts an and as will have no tendency to act as piston and cylinder to compress air within the space they substantially enclose.

A mass of solder 67 fills the space between the outer surface of part 63 and the inner surface of part 611, and secures them together so that parts or and oifrom a rigid unit securing arm and member '31 together in a predetermined relationship. Solder 67 is preferably of a low melting point variety; such types are readily commercially available. A heating coil as is provided around part 61 closely adjacent the two parts 61 and 63 and to the solder 67 that joins them. When heating coil 68 is energized through sequence control '30, as shown, the solder is melted. When this occurs, parts an and as are free to move relative to each other under the influence of spring 48. Spring 54 is stronger than spring 48; thus, arm 45 does not move when the solder 67 is melted. Rather, the arm .45 remains in its same pre-set relationship relative to the switch as given to it at the factory. Spring 48, however, is free to move arms 44 and 45 relative to each other with the solder thus melted; since arm 45 cannot move, arm 44 is pushed to the left until it engages bracket 42. The unbalance sensing arrangement is then completely operative, with arm 44 resting against bracket 42 and with arm 45 in the predetermined desired relationship to button 40 as set by means of screw 58. Switch 36 is actuated at the exact amount of tub vibration which was selected when arm 45 was positioned at the factory.

As will be apparent, spring 48 serves two purposes. It serves as a biasing means for etfecting the automatic adjustment of arm 44 when solder 67 is melted, and it serves as yieldable means for transmitting the motion of the one arm to the other, permitting relative movement between the arms upon over-travel of the tub so as to prevent damage to the switch.

To complete the description of the component parts of this invention, it is to be recalled that operation of button 40 of switch 36 de-energizes solenoid 29 which causes the spin operation to cease and the basket to return to its tumbling speed. At the same time that solenoid 29 is de-energized, terminals 37 and 38 of switch 36 are connected to energize timer motor 39. Motor 39 drives a generally star-shaped cam 69 counterclockwise, as viewed in Fig. 4; as it rotates, the cam is adapted to engage the upper end of a leaf spring 70 with one of its lobes 71. Spring 7th is fixedly mounted at its lower end on the bracket 41a. During rotation, cam 69 bends the upper end of the spring to the right, as viewed in Fig. 4, and this bending continues until such time as the spring is bent far enough that the lobe 71 of the cam can slip over its top. At that time, the spring snaps in the op posite direction, striking the button 41 of switch as to disconnect terminals 37 and 38 and reconnect terminals 57 and 35. This stops the timer motor 39 to stop further movement of cam 69, and at the same time re-energizes solenoid 29 so that another attempt is made to spin the clothes in basket 9. This arrangement is described for purposes of illustration; it will be understood that it does not form a part of the basic invention, and that other mechanical arrangements may be used to sheet the same function, or indeed, as mentioned above, switch 35 may be made to control other types of safety functions.

During the time that motion transmitting device 43 is in use, that is, when centrifugal extraction of liquid from the clothes in basket h is being carried out, heater coil 68 is not energized; thus, the solder 67 firmly maintains parts 61 and 63 together in a rigid unit. Sequence control 36 is so set that during a relatively quiet period of operation of each cycle the coil 68 is energized to melt the solder and permit the arm 44 to adjust itself against bracket 42. Thus the device is always maintained at the proper adjustment because for each operation of the device sequence control 34) will provide a heating of heating coil 63 to melt solder 67 and cause arm 44 to be readjusted against bracket 42. It is contemplated that-the after centrifugal extraction, toward the end of a drying cycle where drying of the clothes is provided, at which time the rotational speed is low and the load in the basket is lightest so that the amount of vibration resulting from rotation of basket is at an absolute minimum. However, it will beunderstood that although less satisfactory results are obtained, it is nonetheless possible to efiect the adjustment before the centrifugal extraction, for instance during a washing operation, since the vibrations encountered at that time are not nearly so great as those encountered as aresult of unbalances within basket 9 during centrifugal extraction operations, and are never large enough to cause tripping of switch 36. Also, the

7 sequencecontrolmaybesosetthatcoillisenergized subsequent to a time all other operations-except energination of the sequence control 30 itself-have ceased. At such a time, of course, there is no rotation whatsoever within the basket and therefore the adjustment of arm 44 against bracket 42 is as accurate as possible. However, to avoid lengthening of the cycle, where a washer-dryer is provided, it is contemplated that the adjustment of arm 44 will preferably take place each cycle during rotation after the centrifugal extraction.

To review briefly the sequence of operations of a machine incorporating the improved unbalance sensing arrangement, I provide first a suitable washing operation, with liquid being introduced through suitable means such as inlet 31 (Fig. 2). Subsequent to this, a suitable number of draining and rinsing operations are provided, followed by a centrifugal extractionof liquid by rapid rotation of basket 9. If there is an unbalance within the basket, bracket 42 pushes against arm 44, the length of the movement increasing with the vibrations as the speed increases and with higher unbalances. lf before full spin speed is obtained the unbalance is tending to become harmful to the machine, bracket 42 pushes arm 44 to such an extent that arm 44 in turn pushes arm 45 through spring 48 against button 40 of switch 36, depressing the same. As explained above, this de-energizes the spin solenoid 29, returning the speed to tumble for a period of time which is determined by the operation of motor 39 and cam 69. When the cam G9 releases spring 70 to push on button 41 of switch 36, the timer motor is de-cnergiled, the spin solenoid is re-energized, and another attempt at spin is made. This may be continued as many times as necessary to effect appropriate balance.

After the rapid rotation, or spin operation, the heaters 32 are energized (not included in the control circuit illustrated in Fig. 4) and the heat drying is conducted for an appropriate amount of time. :Toward the end of the heat drying, when the clothes are substantially dry and the vibration of the basket is at a minimum during its rotation, sequence control 30 energizes coil 68 to melt solder 67 and adjust arm 44 against bracket 42. The operation then terminates with all parts being in readiness for the next use thereof.

While in accordance with the patent statutes, I have shown what at present is considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a machine having an article receptacle and means for rotating the receptacle at high speed: means movable in response to vibration of the receptacle; and unbalance switch operative when actuated to prevent rotation of the receptacle at speeds causing vibrations of a magnitude harmful to the machine; a first member intermediate said movable means and said switch positioned in contact with said movable means; a second member intermediate said movable means and said switch positioned to operate said switch upon being moved a predetermined amount; first biasing means biasing said first and second members apart toward said movable means and said switch respectively; means for limiting the distance said members are biased apart, said limiting means being secured to said first and second members; second biasing means secured to said limiting means yieldably resisting movement of said limiting means away from said movable means toward said switch, said second biasing means being stronger than said first biasing means; means preventing said second member from being moved more than said predetermined amount from said switch; and means securing said first member to said mean comprising a part securedtosaidfirstmember,asecondpartseeuredtosaid limitingmeans,saidpartshavingsurfacesadjacenteach other, a quantity of solder securing said surfaces of said parts together, and heating means adjacent said parts, said heating means being effective when operated to mdt said solder whereby said first biasing means move said first member relative to said second member against said movable means thereby to take up any play which may occur between said first member and said movable means.

2. A machine having an article receptacle; means for rotating said receptacle at tumbling speed and at centrifuging speed; means movable in response to vibrations of said receptacle; an unbalance switch operative when actuated to prevent rotation of said receptacle at speeds causing vibrations of a magnitude harmful to the machine; a first member intermediate said movable means and said switch positioned in contact with said movable means; a second member intermediate said movable means and said switch positioned to operate said switch upon being moved a predetermined amount; first biasing means biasing said first and second members apart toward said movable means and said switch respectively; means for the distance said members are biased apart, said means being secured to said first member and engaging said second member; second biasing means secured to said limiting means yieldably resisting movement of said limiting means away from said movable means toward said switch, said second biasing means being stronger than said first biasing means; means preventing said second member from being moved more than said predetermined amount from said switch; means securing said first member to said limiting means comprising a first part secured to said first member, a second part secured to said means, said parts having surfaces adjacent each other, a quantity of solder securing said surfaces of said parts together, and heating means adjacent said parts and elective when operated to melt said solder; electrically actuated' means for controlling said receptacle rotating means and operative when energized to cause provision of a centrifuging speed; sequence control means controlling said electrical control means to provide a predetermined series of tumble speed and centrifugal speed operations, said sequence control means causing energizetion of said heating means during one of the tumble speed operations of said receptacle at which time said first biasing means move said first member relative to said second member against said movable means thereby to take up any play which may occur between said first member and said movable means.

3. The apparatus defined in claim 2 wherein said sequence control means causes energization of said heating means during a tumble speed operation subsequent to the last centrifugal speed operation of said receptacle.

4. In a machine having an article receptacle and means for rotating the receptacle at high speed: a member movable in response to vibrations of said receptacle; a base;

.an unbalance swireh mounted on said base and operative when actuated to prevent rotation of the receptacle at speeds causing vibrations of a magnitude to the machine; a first arm pivoted on said base intermediate said movable member and said switch and positioned in contact with said movable member; a second arm pivoted on said base intermediate said movable member and said switch, said second member being positioned to operate said switch upon being moved a predetermined amount; a first spring between said first and second arms biasing them to pivot away from each other toward said movable member and said switch respectively; a member for the distance said members are pivoted apart, said member being secured to said first arm and engaging said second arm; a second spring secured at one end thereof to said limiting member and at the other end thereof to said base and yieldably resisting movement of said limiting member away from said movable member toward said switch, wfd second spring being stronger than said first spring; an adjustable member engaging said limiting member and positioned to prevent said second arm from being moved more than said predetermined amount from said switch; and means securing said first arm to said limiting member comprising a first tubular part pivotably secured to said arm, a second tubular part arranged in loosely telescoping relation to said first tubular part and pivotably secured to said plate member, a quantity of solder between said telescoping" tubular parts securing them together, and'an electric heating coil wound around the outer of said tubular parts, said heating coil being effective when operated to melt said solder whereby said first spring moves said first arm relative to said second arm against said movable member thereby to take up any play which may occur between said first arm and said movable member.

5. In a machine having an article receptacle and means for rotating the receptacle at high speed: means movable in response to vibrations of the receptacle; an unbalance switch operative when actuated to prevent rotation of the receptacle at speeds causing vibrations of a magnitude harmful to the machine; a first member intermediate said movable means and said switch positioned in contact with said movable means; a second member intermediate said movable means and said switch positioned to operate said switch upon being moved a predetermined amount; first biasing means biasing said first and second members apart toward said movable means and said switch respectively; means for limiting the distance said members are biased apart, said limiting means being secured to said first member and engaging said second member; second biasing means secured to said limiting means yieldably resisting movement of said limiting means away from said movable means toward said switch, said second biasing means being stronger than said first biasing means; means preventing said second member from being moved more than said predetermined amount from said switch; and means securing said first member to said limiting means comprising a first substantially tubular part pivotably secured at one end to said first member, a second substantially tubular part pivotably secured at one end to said limiting means and positioned in loosely telescoping relation to said first part, a quantity of solder between said telescop ing tubular parts securing them together, and an electric 10 heating coil wound around the outer of said tubular parts and etfective when operated to melt said solder whereby said first biasing means moves said first member relative to said second member against said movable means thereby to take up any play which may occur between said first member and said movable means.

6. In a machine having an article receptacle and means for rotating the receptacle at high speed; means movable in response to vibration of the receptacle; unbalance switch means operative when actuated to prevent rotation of the receptacle at speeds causing vibrations of a magnitude harmful to the machine; a first member intermediate said movable means and said switch positioned to be engageable by said movable means; a second member intermediate said movable means and said switch positioned to be engageable with said switch means to actuate the same; biasing means biasing said first and second members apart toward said movable means and said switch respectively; means for limiting the distance said members are biased apart, said limiting means being secured to said first and second members; means yieldably maintaining one of said members a predetermined distance from the means with which said one member is engageable, said yieldable means being stiffer than said biasing means; and means securing the other of said members to said limiting means comprising a first part secured to said other member, a second part secured to said limiting means, said parts having surfaces adjacent each other, a quantity of solder securing said surfaces of said parts together, and heating means adjacent said parts, said heating means being effective when operated to melt said solder whereby said biasing means is free to move said other member relative to said second member toward the means with which it is engageable to take up any play which may occur as a result of wear and adjustment of the parts of the machine.

References Cited in the file of this patent UNITED STATES PATENTS 2,127,319 Zahrabnik Aug. 16, 1938 2,807,952 Bochan Oct. 1, 1957 2,821,602 Hordechuck Jan. 28, 1958 2,832,208 Stone Apr. 29, 1958 

